利用声作用力改善冲击射流热传导

Time Resolved Particle Image Velocimetry and Infrared Thermography are used to investigate
the behaviour of a round jet impinging on a flat plate for a Reynolds number 28 000, for orificeto-
plate distances of 3 or 5 nozzle diameters and for two different nozzles, a contraction and a long tube.
The contraction nozzle reveals a different heat transfer distribution on the impinging plate compared to
the long tube case, more often used in the literature. The jet is excited by a loudspeaker at Strouhal
numbers 0:26, 0:51 and 0:80. This acoustic forcing changes the jet velocity structure, modifying annular
vortex rings in the shear layer of the jet and increasing the turbulent values in the whole domain of the
jet, including the potential core. The heat transfer is therefore modified, resulting in an increase of the
Nusselt number near the jet axis and an alleviation or a shift of the secondary peak. 时间分辨粒子成像测速系统(TR-PIV)